Apparatus for discharging particulate material



United States Patent [72] Inventor Hus A. Eekhlrdt 2,167,416 7/1939 Carlson 222/195 55 Crescent Bend, Allendale, New Jersey 2,353,346 7/1944 Logan 222/195X 07401 2,803,085 8/1957 Walberg 222/195X (21] Appl. No. 697,081 3,097,828 7/1963 Grun 222/195X [22] Filed Jan. 11, 1968 3,166,222 1/1965 Schrader 222/195 [45] Patented Nov. 17, 1970 3,188,144 6/1965 Gmur et al 222/195X 3,270,463 9/1966 Ashworth et al 222/161X [s4] APPARATUS FOR DISCHARGING PARTICULATE 'f' MATERIAL Assistant xammer-H. ane

9 Claims, 2 Drawing Figs.

[52] U.S. Cl 222/195,

222/226- 302/52 ABSTRACT: An apparatusfor discharging powder, flake, and

Ill-

other particulate materials has a bottom with an interior su [50] Field ofSeai-eh 34/174, 89; fa a c din to a central opening, A spreader above that 222/226, I95, 161, 214/8328; 302/52 opening has a larger radial width than that opening. The bottom and the spreader are provided with means for introducing [56] Rehnmes cited air into the particulate material contained in the apparatus. 7 N D STATES PATENTS Foreign particles are forced to the bottom and are monitored 2,072,845 3/1937 Benoit 222/195X by electricaland magnetic detection means.

. 52 3o flo & :I: fi..

i Elli Z6 Patented Nov. 17, 1970 FIG.

APPARATUS FOR DISCHARGING PARTICULATE MATERIAL This invention relates to apparatus for treating particulate material and in particular to apparatus for treating with a gas, drying, heating, aerating and fluidizing-powdery or granular material in connection with the discharge of such material and with the detection and removal of foreign particles.

To treat powdery, granular or other particulate material with air or other gasesfor the purpose of drying or heating, bins, hopper, and other compartments containing such material are known which receive heated and dry air in their lower part and release it at their upper end. Usually these bins have at the lower conical end a central discharge opening and introduce the air at points above that opening, with the result all portions of the material contained therein are uniformly that portions of the material receive considerably less air flow than others.

Since the air is introduced from the side, conical baffles are often used in the b'ins lower part to distribute the air over the bin's circumference with the consequence that the flow of material in the lower part of the bin is detrimentally affected, often causing congestion and bridging in this area critical for uninterrupted discharge.

Other known devices attempt to solve the difficulties in connection with the discharge by vibrating the lower part of the bin together with a central baffle. While such equipment is suitable for discharging a variety of particulate materials, very sticky and tacky materials which tend to congest and bridge present severe difficulties, since they react adversely to vibration and compaction. Besides, these devices have not been designed for drying, heating and other gas contact operations.

Furthermore, the equipment mentioned above does not provide for the detection and removal of foreign particles which frequently get into the material accidentally during preceding production and handling operations. Such foreign particles often consist of steel, bronze, aluminum, and other metals, or of glass, ceramics, stone, etc. They have again and again caused severe damage to machinery further downstream, such as extrusion screws and liners, injection nozzles and molding dies, calenders and roll mills. Aside from the damage to processing equipment, foreign particlesenclosed in end products have often made large production quantities unusable. The financial losses have been more severe by the lack of efficient methods to check extruded, molded or calendered products for enclosed foreign particles, and therefore the production over an extended period of time has often been scrapped when foreign particles were either actuallyenclosed or only suspected.

Apart from the above-mentioned bins for drying, heating and otherwise treating powdery orgranular material, many at tempts have been made to remove foreign particles from such materials. One approach is sifting the feed material through a screen upstream or downstream of the bin. This method involving an additional operation is only suitable for well-flowing materials, but not for tacky or sticky, materials. Furthermore, only such foreign particles can be screened out which are larger than the largest particle size of the material to be processed. 'Very often the processed material particles are relatively large, as with polymer pellets, granulated chips, comminuted plastic products, and therefore foreign particles of comparable size can still damage equipment and even more so will cause the rejection of large production quantities.

Another method is the use of grate magnets upstream or downstream of the bin. It is obvious that only ferromagnetic particles can be expected to be removed. In the industry, however, stainless steel, bronze, aluminum and other nonmagnetic materials are largely used. Bolts, screws, nuts and other elements made of such metals sometimes come loose from equipment or get otherwise into the material flow. Furthermore, in many operations magnetized bars obstruct the flow of material excessively and therefore cannot be used. In addition, it has been found that even ferromagnetic bodies are not retained by the grate magnets, if the gravity forces overcome the magnetic forces. With electromagnets accidental switching on-off of the electric energy supply, even if for a short moment only,

has dumped the accumulated ferrous metal bodies together in.

the processing equipmem, with even more severe consequences. Sim'ilar occurrences have taken place with permanent magnets after their magnetic fields had decreased below an effective level.

It isan object of the present invention to provide apparatus for treatingparticulate materials in a bin in such a manner that dried, heated, aerated, fluidized or otherwise gas-treated, and to eliminate air baffles inverting the direction of airflow or restricting the material flow.

It is a further object to uniformly discharge difficult materials from the bin and to eliminate bridging, rat-holing and congestion. 4

It is a further object toreliably monitor and safely retain foreign particles in the bin,

Generally speaking, the present invention contemplates an improvement in an apparatus for drying, heating, aerating, fluidizing and otherwise gas-treating particulate material, comprising a bin or other compartment for receiving material, having a bottom with a central opening and an interior surface ascending to that opening which is located above the lowest portion of the bottoms interior surface. The compartment is I means based on principles of magnetism, electricity or radiation are provided to detect and to retain foreign particles in the compartment.

These and othervfeatures, advantages, objects and uses will become apparent by reference to the following description when taken in connection with the accompanying drawings showing preferredembodiments, wherein;

FIG. 1 is an elevational view, partly in section, of one em bodiment of the apparatus; and

FIG. 2 is an elevational view, partly in section, of another embodiment of the apparatus.

' Referring to thedrawings, FIG. 1, there is shown an apparatus for treating particulate'material with air or other gases. A compartment 10 for receiving material has a bottom 12 with acentral opening 14 therein and an interior surface 16 ascending to the opening Which is located above the lowest portion of the interior surface of the bottom 12. A discharge duct 18 extends downward from the opening 14. The compartment 10 is provided in its lower part with means for introducing air or other gases into the material, comprising the gas-permeable plates 20, the covers 22 and the ducts 24 mounted in three sectorial sets between the radial ribs 26.

A spreader 28 positioned abovethe opening 14 has a substantially larger radial width than the opening 14 and has an increase in radial width in downward direction. The spreader 28 having a gas-permeable cone 30 is provided with means for introducing air or other gases into the material, including the gas-permeable tubes 32 holding the spreader 28 in position,

the passageways 34 through the radial ribs 26, and the ducts 36. The latter elements are mounted as three sets at the three radial ribs 26 which form three rigid connections between the compartment 10 and the discharge duct 18.

The plates 20, the cone 30 and the tubes 32 are gas-permeable by using porousmaterials for their construction. Instead, gas-'permeability can be achieved in other ways, for example. by using materials with perforations, woven cloth, screens or nozzles with filter screens providing openings for the gas smaller than the smallest particle size of the processed material.

The lower part of the compartment 10 is provided with magnetic means to pull magnetic particles to the interior surface 16 of the compartment 10. While permanent magnets between the conductive perforated plates 120 and the conductive members 143. With the switch 147 closed, they cause a current to flow through the signal light 148. Single conductive particles which are too small to bridge that distance will not alarm the operator, but if large numbers accumulate, they will form a conductive bridge. Principally, the size of conduc-w somewhat tacky, sticky or cohesive, the agitator 133 is provided. Theelements 134, 135, 136 out out of the material a ring of triangular cross section which gradually sinks down toward the bottom 112 at thesame time being sliced into thin horizontal layers by the element 136. Into the area thus being vacated sinks an upper ring of material with a cross section determined by the spreader l28, the shaft 129 and the members 134, 137, and this ring is being shaved in the form of thin layers by the member 134 into the space being vacated. Into the space vacated by that upper ring of material sinks down the material from the upper part of the compartment 110, also sliced into thin layers by the member 137.

The agitator 133 is provided with a larger distance to the tapered sidewall of the compartment 110, when the spreader 128 is mounted for axial movement to vary the flow cross section between the opening 114 and the spreader 128. in the lowest position the spreader 128 covers the opening 114 and thus serves as a bottom closure of the compartment 110. The compartment 110 can then be emptied, for instance, after removing the covers 122 and plates 120.

in order to shut off the flow from the upper portion of the compartment 110 to the bottom 112 between the periphery of the spreader 128 and the tapered sidewall of the compartment 110, the spreader 128 is equipped, with a radial width sufficiently large that in its lowest position it contacts the tapered sidewall of the compartment 110. In the area of this circumferential contact line the sidewall of the compartment 110 is preferably more tapered toward the horizontal plane. With the spreader 128 in this lowest position,'the covers 122 and the plates 120 can be removed, preferably by hinge connections, for inspection and cleanout, with the compartment 110 full all the way above that circumferential contact line.

Although the present invention has been described in conjunction with particular embodiments, it is apparent to those skilled in the art that modifications and variations are possible opening therein through which the particulate material discharges downward, the central opening having a horizontal dimension which is larger than one-tenth of the horizontal dimension of 'said' bottom projected to the horizontal plane through the upper end of said opening, the interior surface of:

said bottom ascending with angles of less than 90 to the horizontalin a continuous, unbroken and smooth ascent to said opening which is located above the lowest portion of said interior surface. 3 I

2. Apparatus for discharging particulate material as claimed in claim 1 wherein the bottom forming a continuous, unbroken and smooth interior surface in the inclined ascent to the opening is made of gas-permeable material over more than one-eighth of the interior surface of said bottom and is provided with'means for introducing a gas through said gaspermeable material into the compartment.

without departing from the spirit and scope of the invention.

For instance, the opening and the spreader may be off center of the compartment; the axis of the'compartment or of the spreader or both may be tilted from the vertical position; more than one opening and spreader may be applied; the odd numbers of laminae and of electrically conductive members may be exchanged against the even numbers and vice versa; vari-' ous types of baffles may be used to improve the flow of air and of the material; besidesair, other gases may be applied, especially when certain reactions are to be performed or prevented, respectively, such as reducing, oxidizing, calcining, activating, or purging with an inert gas.

In the described embodiments surfacesare shown to be provided for sealing against gases and the material. The seals, however, are not shown because of their size and for better clarity. Also not shown are bolts, screws, nuts to connect parts shown as being provided with flanges for such connections.

Such modifications and variations are considered to be within the purview and scope of the invention and appended claims.

lclaim:

1. Apparatus for discharging particulate material compris- 3. Apparatus for discharging particulate material as claimed in claim 1 wherein a spreader is positioned in its entirety above the opening and above at least a portion of the smoothly and continuously ascending bottom surface and comprises a nonperforated substantially horizontal plate with a horizontal dimension which is between 5 and ISO percent larger than the horizontal dimension of the opening, and a cone connected with its large circumference to said nonperforated plate and decreasing in upward direction in radial width.

4. Apparatus for discharging particulate material as claimed in claim 3 wherein the spreader is attached to a vertical shaft mounted rotatably and is connected with an agitator having an element extending from the outward portion of said spreader in an outward and upward direction to a point near the interior compartment wall, and a second element extending from said point inward to said shaft, so that the material outside and under said element is separated by said agitator from the material inside and above said element.

5. Apparatus for discharging particulate materials as claimed in claim 3 wherein between the horizontal plate'of the spreaderand the'continuously ascending bottom at least two substantially vertical members are provided, at least one member having a conduit and being provided with means for introducing a gas between the cone of the spreader increasing in radial width in downward direction, and the spreaders plate extending substantially in horizontal direction and, forming with said cone an angle of less than into the compartment,

, 6. Apparatus for discharging particulate material as claimed in claim 3 wherein the bottom of the compartment-ascends over an .interior surface area larger than the vertical downward projection of the spreader covers, to the central opening continuously and smoothly with an angle of less than 90 to the horizontal, and means for vibrating said bottom and said spreader are provided.

7. Apparatus for discharging particulate material as claimed in claim 3 wherein the spreader with a substantially horizontal plate surface is axially moveable to the openings upper rim to decrease the flow of material, and is axially moveable from 'said rim to increase the flow of material.

8. Apparatus for discharging particulate material as claimed in claim 7 wherein the spreader in its lowest position closes the flow of material across a circumferential line formed between the substantiallyhorizontal plate surface of said spreader and said openings upper rim. 1

9. In an apparatus for discharging particulate material comprising a compartment for receiving material having a bottom with a central opening therein and an interior surface ascending to said opening which is located above the lowest portion of said interior surface, the improvement therein comprising an access door provided in the lower part of the compartment for easy access to the interior surface of said compartment and a shutoff gate above said access door to open and close the flow of material toward said opening. 

